# ---
# title: 222. Count Complete Tree Nodes
# id: problem222
# author: Tian Jun
# date: 2020-10-31
# difficulty: Medium
# categories: Binary Search, Tree
# link: <https://leetcode.com/problems/count-complete-tree-nodes/description/>
# hidden: true
# ---
# 
# Given a **complete** binary tree, count the number of nodes.
# 
# **Note:**
# 
# **_Definition of a complete binary tree
# from[Wikipedia](http://en.wikipedia.org/wiki/Binary_tree#Types_of_binary_trees):_**  
# In a complete binary tree every level, except possibly the last, is completely
# filled, and all nodes in the last level are as far left as possible. It can
# have between 1 and 2h nodes inclusive at the last level h.
# 
# **Example:**
# 
#     
#     
#     Input: 
#         1
#        / \
#       2   3
#      / \  /
#     4  5 6
#     
#     Output: 6
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
